Several types of plugging devices for plugging of hydrocarbon well pipes are known. In U.S. Pat. No. 7,178,602 (also in the name of Brønnteknologiutvikling) it is shown a plugging device having an anchoring device with gripping elements for anchoring the plugging device to the inner casing of the well pipe to prevent movement of the plugging device. The plugging device also comprises an expandable packer element for sealing the well pipe. The packer element is supported by a link connection for compressing and thereby expanding the packer element radially.
A so-called high expansion plugging device has a relatively narrow diameter in retracted state, allowing the plugging device to pass restrictions in the well pipe. At the same time, it has a relatively large diameter in expanded state to seal the well pipe.
In some subsea hydrocarbon well pipes, there is a need for plugging devices which may withstand high pressures and high temperatures for a long time. This puts a lot of stress to the packer element being compressed during the sealing period. Moreover, it is a requirement that the plugging device is retrievable from the well after use. Often there is a risk that the packer element becomes deformed during the expansion, which may cause problems with retrieving the plugging device past narrow restrictions in the well pipe.
The object of the invention is to provide a plugging device which is capable of withstanding a high pressure and a high temperature for a long time and still being able to be retracted after use.